Frost nodded. He looked out over the Atlantic. The blue surface shimmered beneath them. He tried to imagine the water rising up in a six-hundred-metre dome.

'No problem,' he said. 'We could do with one.'

Independence, Greenland Sea

Samantha Crowe put down her notes and stared out of the window. The CH-53 Super Stallion was descending rapidly. A strong gust pummelled the heavy-lift helicopter. The thirty-metre craft seemed to be plummeting towards the light-grey surface stationed in the sea. Crowe was astonished that a vessel of such colossal proportions was capable of staying afloat, but at the same time she couldn't help wondering if it was big enough to land on.

Nine hundred and fifty kilometres to the north-east of Iceland, the USS Independence LHD-8 was sailing over the deep-sea basin of the Arctic Ocean, a floating city in the Greenland Sea. Like the spaceship in Alien, its presence seemed dark and foreboding. Two hectares of freedom and 97,000 tonnes of diplomacy – as the US Navy liked to say. The amphibious-assault helicopter-carrier, the largest of its kind in the world, would be her home for the next few weeks. Samantha Crowe, c/o USS Independence LHD-8, latitude 75 degrees north, 3500 metres above the ocean floor.

Her mission: to conduct a conversation.

The helicopter banked. The Super Stallion rushed towards the landing point and touched down with a bounce. Through the side-window she saw a man in a yellow shirt directing the helicopter into its bay. One of the crew reached over and unfastened her seat-belt, then helped her out of her lifejacket, goggles, safety helmet and ear-protectors. The flight had been turbulent, and Crowe felt unsteady on her legs. She teetered down the ramp at the rear of the helicopter, crossed beneath the tail of the Super Stallion and looked around.

Only a few helicopters were visible on the flight deck. Her eyes roved over the endless expanse of asphalt, 257.25 metres long, 32.6 metres across, and dotted with bollards. Crowe knew the exact dimensions. She was a mathematician who loved precision, and she'd found out as much as she could about the Independence before she'd set out. At present, the statistics were dwarfed by reality: the Independence was much greater than its technical specifications, schematics and plans. The air smelt strongly of kerosene and oil, mixed with a hint of salt and overheated rubber. A fierce wind swept the combination of odours over the flight deck and tugged at her overalls.

Not the kind of place you'd choose to visit.

Men in brightly coloured shirts and protective headphones ran back and forth. A white shirt headed towards her. Crowe racked her brains. White was the colour for safety personnel. The men in yellow directed the helicopters in to land, and the red shirts were responsible for fuel and ammunition. Weren't there brown shirts too? And maybe purple. What were the brown shirts for?

'Follow me,' the man bellowed over the noise of the slowing rotor. He gestured towards the superstructure. It rose up on the starboard side of the deck like a high-rise apartment block, crowned with oversized antennae and sensors. Crowe's right hand reached down automatically to her pocket. Then she remembered that her cigarettes were stashed beneath her overalls. She hadn't been able to smoke in the helicopter either. Flying to the Arctic in high winds hadn't bothered her, but holding out without nicotine for hours on end was no laughing matter.

The man opened a hatch and Crowe stepped into the superstructure, or the island, as the sailors called it. Once they'd passed through another door into the interior, they were greeted by a wave of clean air. In Crowe's view, the island looked more like a cave. It was incredibly cramped inside. The white shirt delivered her into the care of a tall black man in uniform, who introduced himself as Major Salomon Peak. As they shook hands, Peak seemed rather formal, as though he had little experience of dealing with civilians. Crowe had spoken to him several times over the past few weeks, but only ever by phone. They strode along a winding corridor and clambered down a series of steep companionways deep into the bowels of the ship. The soldiers followed with her bags. On one of the bulkheads, a sign proclaimed, in big letters, '02 LEVEL'.

'I expect you'll want to freshen up,' said Peak. He opened one among many identical doors lining both sides of the passageway. It led into a surprisingly spacious and pleasantly decorated cabin, more a suite than a room. Crowe had read somewhere that living space on helicopter-carriers was kept to a minimum and that the troops slept in dormitories. Peak raised his eyebrows when she commented.

'We'd hardly make you sleep with the marines,' he said. The hint of a smile played on his lips. 'The navy knows how to look after its guests. This is flag accommodation.'

'Flag?'

'Our very own Hilton. Living-quarters for admirals and their staff. We're not at full capacity, so we've got all the space in the world. We've given the flag accommodation to women and the men have been housed in officer berthing. May I?' He walked ahead of her and opened another door. 'Bathroom.'

'I'm impressed.'

The soldiers brought in her bags.

'There's a minibar under the TV,' said Peak. 'Soft drinks only. I was thinking I'd come back in thirty minutes so we can start the tour. Will that be sufficient?'

'Absolutely.'

Crowe waited until the door had closed behind him, then hunted for an ashtray. She found one in a sideboard, peeled off her overalls and rummaged through her jacket pockets. It wasn't until she'd opened the crumpled packet, lit the cigarette and taken a drag that she started to feel properly alive.

She sat on the edge of her bed. Two packs a day. She couldn't give up. She'd tried twice and failed.

Maybe her heart wasn't in it.

After a second cigarette, she showered, then pulled on some jeans, sneakers and a sweater. She smoked a third cigarette, and opened all the cupboards and drawers. By the time she heard a knock at the door, she'd already inspected the inside of her cabin so thoroughly that she could have drawn up an inventory from memory. She liked to know how things stood.

It wasn't Peak in the passageway, but Leon Anawak.

'I told you we'd meet again,' he grinned.

Crowe laughed. 'And I told you that you'd find your whales. Good to see you, Leon. I hear you're the one I need to thank for being here.'

'Who told you that?'

'Li.'

'Oh, I reckon you'd he here anyway. I had a dream about you.'

'Oh, my.'

'Don't worry – you were a kind of friendly spirit. How was the flight?'

'A bit humpy. Am I the last to arrive?'

'The rest of us boarded in Norfolk.'

'I couldn't get away from Arecibo. You wouldn't believe how much effort it takes to stop working on a project. We had to close down SETI. No one's got the cash to look for little green men at the moment.'

'There's a good chance you'll find more of them than you bargained for,' said Anawak. 'Are you ready? Peak will be here in a moment. He'll show you what the Independence has to offer and then it's your turn. Everyone's really excited. You've already got a nickname, by the way.'